On July 23, Turkey finally joined the fight against the Islamic State (also known as ISIS), and it did so with much fanfare. It began with a series of air and artillery strikes to push back ISIS forces in Syria and seal what has been a porous southern border. The Turkish government also gave the United States access to its Incirlik and Diyarbakir airbases, opening them up to support combat missions, not just surveillance operations.

This was a major win for the Obama administration, which, for months, had been negotiating with a reluctant Turkey to get it to recognize the ISIS threat. U.S. officials are now hopeful that ISIS can be set back on its heels, since Ankara will be able to wage a more robust bombing campaign given its proximity to the conflict. The U.S.–Turkish agreement about the Incirlik and Diyarbakir airbases apparently also involved the establishment of a safe zone in northwest Syria just north of Aleppo, something the Turkish government has long demanded, although Washington has refused to commit to it. Turkish Foreign Minister Mevlut Cavusoglu has argued that a safe zone would naturally emerge after removing ISIS forces from that part of Syria.

Umit Bektas / Reuters

Kurdish men pose for a picture in front of a Kurdistan Workers Party (PKK) flag, March 17, 2015.

Yet all is not as it seems. Although Washington trumpeted the agreement as a potential game changer in the fight against ISIS, Ankara’s recent behavior suggests that its primary mission is to use the opportunity to simultaneously fight the Kurdistan Workers’ Party (PKK), a Kurdish separatist group that the government has been fighting for decades. The group, however, has also been on the frontlines battling ISIS.

As Washington celebrated Turkey’s new commitment, Ankara’s initial airstrikes last week targeted both ISIS and PKK positions, and, as some have noted, the United States has essentially enabled Turkey to cloak its primary objective—striking the PKK and its Syrian cousin, the People’s Protection Units (also known as the YPG)—in the general fight against ISIS. Turkey would also be able to